Place flour in a food processor. While motor is running, add 1/2 cup warm water to form a slightly sticky dough. Knead on a well-floured surface until uniform and smooth, about 3 minutes. Place under a damp towel for at least 30 minutes.

Meanwhile, make sauce: Combine all ingredients except chilies in a small bowl. Stir until sugar has dissolved. Add chilies or wait until just before serving (the longer they're in, the hotter the sauce gets).

Continue making pancakes by combining sesame oil, vegetable oil, and salt in a small bowl. Cut dough in half, then cut each half into 3 even pieces. Form each into a ball, and work with 1 ball at a time (keep others covered with damp towel). Roll out on a well-floured surface into a thin circle (about 1/16-inch thick). Spread a teaspoon of oil mixture evenly over pancake, and sprinkle with 1 teaspoon sesame seeds and 1 tablespoon scallions. Roll up from one end like a jelly roll, then coil roll around to form a spiral; pinch end to roll so it stays in place. Press spiral with your palm to flatten it, then roll out pancake to 1/8-inch thick; set aside. Repeat process with remaining balls.

Heat 1 tablespoon vegetable oil in a pan over medium-low heat. Set 1 pancake in pan; sauté until crisp and golden, about 1 minute. Flip and brown other side. Remove to a plate and cover with foil to keep warm. Repeat for other pancakes; add more oil as needed.

Cut each pancake into 4 to 6 pieces. Serve immediately with sauce on the side.